1. Field of the Invention
The present invention relates to ceiling fans and more particularly ceiling fans including heaters and heater attachments for ceiling fans.
2. Brief Description of the Prior Art
Ceiling fans are well known as effective means for circulating air in enclosed spaces. They are employed chiefly in warm weather conditions for cooling and ventilating rooms. The fans, which are typically centered in the ceiling of a room, employ relatively large blades (for example, about one half meter in length) circulating at low speeds (for example, about 130 rpm), and are typically operated to push air downward in the center of the room, the air returning to the fan proximate the walls and ceiling of the room. Because ceiling fans are typically operated at low speeds, they operate quietly, which is very desirable for the room's occupants.
While ceiling fans are used almost exclusively under warm conditions, they are also of potential value in cool and cold weather, when enclosed spaces must be heated. Since hot air rises, rooms tend to be heated from the top down, lengthening the discomfort endured by their occupants from the cold, particularly when ceilings are high. This is also wasteful of energy, because the upper portion of a room is not occupied. Because they tend to bring air close to the ceiling of a room down towards the center of the room, ceiling fans can increase the comfort of occupants of cold rooms while they are being heated through their circulation of the room's air, and reduce energy costs. On the other hand, the slight draft they create, so pleasant on a sultry day, may have the opposite effect on a cold one.
A number of efforts have been made in the prior art to provide ceiling fans themselves with means for heating the room. One popular direction, exemplified in U.S. Pat. Nos. 4,782,213 and 4,504,191 has been to attempt to fit the fan blades themselves with heating elements. This has the inherent difficulty of requiring moving electrical contacts for the heater circuits, which must carry a relatively large current if they are to effectively heat the room. A further difficulty lies in the proximity of the fan blades to the ceiling, which tends to promote heat loss to the ceiling.
A second approach has been to mount heating elements in the vicinity of the fan blades, so that air to be heated is drawn or pushed over the heating elements. This second approach, which is exemplified in U.S. Pat. Nos. 5,077,825, 5,333,235, and 5,425,126, also inherently suffers from a number of serious drawbacks.
If the heating elements are mounted below the fan blades, such as in U.S. Pat. Nos. 5,077,825 and 5,333,235, aesthetics and consumer acceptance dictate that they be near the fan's rotational axis. However, in this case the ceiling fan motor immediately above them must be provided with substantial thermal protection. Further, the air flow from the rotating blades is minimal proximate the rotational axis, limiting heat transfer from the heating elements to the circulating air. These factors substantially limit the amount of heat that can be safely provided. Conversely, if the heating elements are disposed above the fan blades, such as in U.S. Pat. No. 5,425,126, not only the fan motor, but also the ceiling, must be thermally insulated from the heating elements. In the device shown in the '126 patent the fan is operated backwards, blowing air up over the heating elements. Unless special arrangements are otherwise made, circulating air in this way will wastefully heat the ceiling and walls before the center of the room. Thus, in the '126 device the heated air is pushed through a set of tubes arranged to spill the heated air just outside and below the radial sweep of the ceiling fan blades, so that the heated air is delivered to the center of the room. However, these tubes give the device an unconventional appearance, reducing consumer acceptance.
It is an object of the present invention to overcome the several disadvantages of the prior art, and to provide a ceiling fan room heater which effectively and comfortably heats an enclosed space in cool and cold weather and which can be used in a conventional manner to circulate the air and ventilate the enclosed space in warm and hot weather. An important object of this invention is to provide a ceiling fan room heater which delivers heat quietly. It is a further object of the present invention to provide a heating assembly adapted for mounting on an existing ceiling fan to provide heat in an efficient, effective and comfortable manner. It is also an object of this invention to provide for an existing ceiling fan a heating assembly which can be easily installed on the ceiling fan. Another object of the present invention is to provide a heating assembly for a ceiling fan which is unobtrusive, and which can be matched to the style and finish of the ceiling fan. Yet another object of this invention is to provide a heating assembly for ceiling fans which can be used with lighting accessory kits similar to those conventionally provided for such fans.